The move marks just the latest activity among mobile companies hoping to wring value from their patents, as competition heats up in the smartphone market and companies look for any way to gain an edge.

"There may be multiple ways to realize such value given the current heightened market demand for intellectual property in the mobile telecommunications industry," according to the filing.

Motorola surely isn't alone among companies wondering if they can follow in Nortel's footsteps. "You had the Nortel sale and now everyone is saying 'what about me,'" said Jonathan Goldberg, an analyst with Deutsche Bank

It's not entirely clear what options Motorola might have, but a clever deal could bring in an immediate investment, he said.

Because Motorola wouldn't want to lose the rights to use its patents, it would presumably structure a sale such that it could continue to use them, Goldberg said. "Whether that's viable from a financial or legal perspective, I don't know," he said. "It seems to me that selling all your patents sounds like a great idea but I think in practice it'd be difficult."

In a statement, Motorola said that it continuously reviews its strategic direction and that it has achieved solid revenue growth in part due to a strong patent portfolio that includes 17,500 patents and 7,500 pending.

The sudden activity around mobile patents comes as competition in the smartphone market heats up. Many of the largest companies have taken the battle for market share to the courts, where the company with the largest patent portfolio typically wins.

In addition to the Nortel patents, which went to a group of companies including Apple, Research In Motion, Microsoft, Ericsson and Sony, InterDigital is also now considering a sale of the company. Apple and Google are rumored suitors for InterDigital, which has more than 8,000 mobile patents.

Other mobile companies have begun to look for licensing revenues from their patents, but they aren't likely to build the kind of stable revenue stream that Qualcomm has, Goldberg said. Qualcomm is the best-known example of a company in the mobile market that has consistently been able to earn a significant portion of its revenue from patent licensing, he said. While both Nokia and Microsoft this week discussed earnings from patent royalties, Nokia is unlikely to be able to rely on a steady stream of royalties going forward and Microsoft is unlikely to have serious interest in straying from its core software business to focus on patent royalties, he said.

Many of the largest players in the industry are currently waging patent infringement battles in the courts. Apple has sued Motorola, Samsung and HTC over their Android products. Microsoft persuaded HTC and others to license its technology for use in their Android products, and Oracle is suing Google over Android.